Ginkgo biloba Early | |
---|---|
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Gymnospermae |
Division: | Ginkgophyta |
Class: | Ginkgoopsida |
Order: | Ginkgoales |
Family: | Ginkgoaceae |
Genus: | Ginkgo |
Species: | G. biloba |
Binomial name | |
Ginkgo biloba | |
Synonyms [4] | |
|
Ginkgo biloba, commonly known as ginkgo or gingko ( /ˈɡɪŋkoʊ,ˈɡɪŋkɡoʊ/ GINK-oh, -goh), [5] [6] also known as the maidenhair tree, [7] is a species of gymnosperm tree native to East Asia. It is the last living species in the order Ginkgoales, which first appeared over 290 million years ago, and fossils very similar to the living species, belonging to the genus Ginkgo , extend back to the Middle Jurassic epoch approximately 170 million years ago. [2] The tree was cultivated early in human history and remains commonly planted, and is widely regarded as a living fossil.
Ginkgo leaf extract is commonly used as a dietary supplement, but there is insufficient clinical evidence that it supports human health or is effective against any disease. [8] [9]
The genus name is regarded as a misspelling of the Japanese pronunciation gin kyo ( [ɡiŋkʲoː] ) for the kanji 銀杏 meaning "silver apricot", [10] which is found in Chinese herbology literature such as 日用本草 (Daily Use Materia Medica) (1329) and Compendium of Materia Medica 本草綱目 published in 1578. [11]
Despite its spelling, which is due to a complicated etymology including a transcription error, "ginkgo" is usually pronounced /ˈɡɪŋkoʊ/ , which has given rise to the common alternative spelling "gingko". The spelling pronunciation /ˈɡɪŋkɡoʊ/ is also documented in some dictionaries. [12] [13]
Engelbert Kaempfer first introduced the spelling ginkgo in his book Amoenitatum Exoticarum. It is considered that he may have misspelled "Ginkjo" or "Ginkio" (both consistent with his treatment of Japanese kyo in the same work) as "Ginkgo". This misspelling was included by Carl Linnaeus in his book Mantissa plantarum II [14] and has become the name of the tree's genus. [15] [12] The specific epithet biloba is New Latin for "two-lobed".
Ginkgos are large trees, normally reaching a height of 20–35 m (66–115 ft), [16] with some specimens in China being over 50 m (165 ft). The tree has an angular crown and long, somewhat erratic branches, and is usually deep-rooted and resistant to wind and snow damage. Young trees are often tall and slender, and sparsely branched; the crown becomes broader as the tree ages. A combination of resistance to disease, insect-resistant wood, and the ability to form aerial roots and sprouts makes ginkgos durable, with some specimens claimed to be more than 2,500 years old. [17]
The leaves are unique among seed plants, being fan-shaped with veins radiating out into the leaf blade, sometimes bifurcating (splitting), but never anastomosing to form a network. [18] Two veins enter the leaf blade at the base and fork repeatedly in two; this is known as dichotomous venation. The leaves are usually 5–10 cm (2–4 in), but sometimes up to 15 cm (6 in) long. The old common name, maidenhair tree, derives from the leaves resembling pinnae of the maidenhair fern, Adiantum capillus-veneris . Ginkgos are prized for their autumn foliage, which is a deep saffron yellow. [19]
Leaves of long shoots are usually notched or lobed, but only from the outer surface, between the veins. They are borne both on the more rapidly growing branch tips, where they are alternate and spaced out, and also on the short, stubby spur shoots, where they are clustered at the tips. Leaves are green both on the top and bottom [20] and have stomata on both sides. [21] During autumn, the leaves turn a bright yellow and then fall, sometimes within a short space of time (one to fifteen days). [22]
Ginkgo branches grow in length by growth of shoots with regularly spaced leaves, as seen on most trees. From the axils of these leaves, "spur shoots" (also known as short shoots) develop on second-year growth. Short shoots have short internodes (they may grow only one to two centimeters in several years) and their leaves are usually unlobed. They are short and knobby, and are arranged regularly on the branches except on first-year growth. Because of the short internodes, leaves appear to be clustered at the tips of short shoots, and reproductive structures are formed only on them (see pictures below – seeds and leaves are visible on short shoots). In ginkgos, as in other plants that possess them, short shoots allow the formation of new leaves in the older parts of the crown. After a number of years, a short shoot may change into a long (ordinary) shoot, or vice versa.[ citation needed ]
Ginkgo prefers full sun and grows best in environments that are well-watered and well-drained. The species shows a preference for disturbed sites; in the "semiwild" stands at Tianmu Mountains, many specimens are found along stream banks, rocky slopes, and cliff edges. Accordingly, ginkgo retains a prodigious capacity for vegetative growth. It is capable of sprouting from embedded buds near the base of the trunk (lignotubers, or basal chichi) in response to disturbances, such as soil erosion. Old specimens are also capable of producing aerial roots on the undersides of large branches in response to disturbances such as crown damage; these roots can lead to successful clonal reproduction upon contacting the soil. These strategies are evidently important in the persistence of ginkgo; in a survey of the "semiwild" stands remaining in Tianmushan, 40% of the specimens surveyed were multi-stemmed, and few saplings were present. [23] : 86–87
Ginkgo biloba is dioecious, with separate sexes, some trees being female and others being male. [24] Male plants produce small pollen cones with sporophylls, each bearing two microsporangia spirally arranged around a central axis.
Female plants do not produce cones. Two ovules are formed at the end of a stalk, and after wind pollination, [25] one or both develop into fruit-like structures containing seeds. The fruits are 1.5–2 cm long, with a soft, fleshy, yellow-brown outer layer (the sarcotesta) that is attractive in appearance, but contains butyric acid [26] (also known as butanoic acid) and smells foul like rancid butter or vomit [27] when fallen. Beneath the sarcotesta is the hard sclerotesta (the "shell" of the seed) and a papery endotesta, with the nucellus surrounding the female gametophyte at the center. [28]
The fertilization of ginkgo seeds occurs via motile sperm, as in cycads, ferns, mosses, and algae. The sperm are large (about 70–90 micrometres) [29] and are similar to the sperm of cycads, which are slightly larger. Ginkgo sperm were first discovered by the Japanese botanist Sakugoro Hirase in 1896. [30] The sperm have a complex multi-layered structure, which is a continuous belt of basal bodies that form the base of several thousand flagella which have a cilia-like motion. The flagella/cilia apparatus pulls the body of the sperm forwards. The sperm have only a tiny distance to travel to the archegonia, of which there are usually two or three. Two sperm are produced, one of which successfully fertilizes the ovule. Fertilization of ginkgo seeds occurs just before or after they fall in early autumn. [18] [28] Embryos may develop in the seeds before or after they drop from the tree. [31]
Chinese scientists published a draft genome of Ginkgo biloba in 2016. [32] The tree has a large genome of 10.6 billion DNA nucleobase "letters" (the human genome has three billion) and about 41,840 predicted genes [33] which enable a considerable number of antibacterial and chemical defense mechanisms. [32] 76.58% of the assembled sequence turned out to be repetitive sequences. [34]
In 2020, a study in China of ginkgo trees up to 667 years old showed little effects of aging, finding that the trees continued to grow with age and displayed no genetic evidence of senescence, and continued to make phytochemicals indefinitely. [35]
Extracts of ginkgo leaves contain phenolic acids, proanthocyanidins, flavonoid glycosides, such as myricetin, kaempferol, isorhamnetin, and quercetin, and the terpene trilactones ginkgolides and bilobalides. [9] [36] [37] The leaves also contain unique ginkgo biflavones, alkylphenols, and polyprenols. [37]
The older Chinese name for this plant is 銀果, meaning "silver fruit", pronounced yínguǒ in Mandarin or Ngan-gwo in Cantonese. The current commonly used names are 白果 (bái guǒ), meaning "white fruit", and 銀杏 (yínxìng), meaning "silver apricot". The name 銀杏 was translated into Japanese as イチョウ (ichou) or ぎんなん (ginnan) and into Korean as 은행 (eunhaeng).
Carl Linnaeus described the species in 1771, the specific epithet biloba derived from the Latin bis, "twice" and loba, "lobed", referring to the shape of the leaves. [38] Two names for the species recognise the botanist Richard Salisbury, a placement by Nelson as Pterophyllus salisburiensis and the earlier Salisburia adiantifolia proposed by James Edward Smith. The epithet of the latter may have been intended to denote a characteristic resembling Adiantum , the genus of maidenhair ferns. [39]
The scientific name Ginkgo is the result of a spelling error that occurred three centuries ago. Kanji typically have multiple pronunciations in Japanese, and the characters 銀杏 used for ginnan can also be pronounced ginkyō. Engelbert Kaempfer, the first Westerner to investigate the species in 1690, wrote down this pronunciation in the notes that he later used for the Amoenitates Exoticae (1712) with the "awkward" spelling "ginkgo". [40] This appears to be a simple error of Kaempfer; taking his spelling of other Japanese words containing the syllable "kyō" into account, a more precise romanization following his writing habits would have been "ginkio" or "ginkjo". [15] Linnaeus, who relied on Kaempfer when dealing with Japanese plants, adopted the spelling given in Kaempfer's "Flora Japonica" (Amoenitates Exoticae, p. 811). Kaempfer's drawing can be found in Hori's article. [11]
The relationship of ginkgo to other plant groups remains uncertain. It has been placed loosely in the divisions Spermatophyta and Pinophyta, but no consensus has been reached. Since its seeds are not protected by an ovary wall, it can morphologically be considered a gymnosperm. The apricot-like structures produced by female ginkgo trees are technically not fruits, but are seeds that have a shell consisting of a soft and fleshy section (the sarcotesta), and a hard section (the sclerotesta). The sarcotesta has a strong smell that most people find unpleasant.[ citation needed ]
The ginkgo is classified in its own division, the Ginkgophyta, comprising the single class Ginkgoopsida, order Ginkgoales, family Ginkgoaceae, genus Ginkgo and is the only extant species within this group. It is one of the best-known examples of a living fossil, because Ginkgoales other than G. biloba are not known from the fossil record after the Pliocene. [41] [42]
Ginkgo biloba is a living fossil, with fossils recognisably related to modern ginkgo from the early Permian (Cisuralian), with likely oldest record being that of Trichopitys from the earliest Permian (Asselian) of France, over 290 million years old. [44] The closest living relatives of the clade are the cycads, [23] : 84 which share with the extant G. biloba the characteristic of motile sperm.
Such plants with leaves that have more than four veins per segment have customarily been assigned to the taxon Ginkgo, while the taxon Baiera is used to classify those with fewer than four veins per segment. Sphenobaiera has been used for plants with a broadly wedge-shaped leaf that lacks a distinct leaf stem.[ citation needed ]
Fossils attributable to the genus Ginkgo first appeared in the Middle Jurassic. The genus Ginkgo diversified and spread throughout Laurasia during the Jurassic and Early Cretaceous. [44]
The Ginkgophyta declined in diversity as the Cretaceous progressed, and by the Paleocene, Ginkgo adiantoides was the only Ginkgo species left in the Northern Hemisphere, while a markedly different (and poorly documented) form persisted in the Southern Hemisphere. Along with that of ferns, cycads, and cycadeoids, the species diversity in the genus Ginkgo drops through the Cretaceous, at the same time the flowering plants were on the rise; this supports the hypothesis that, over time, flowering plants with better adaptations to disturbance displaced Ginkgo and its associates. [23] : 93
At the end of the Pliocene, Ginkgo fossils disappeared from the fossil record everywhere except in a small area of central China, where the modern species survived.
It is doubtful whether the Northern Hemisphere fossil species of Ginkgo can be reliably distinguished. Given the slow pace of evolution and morphological similarity between members of the genus, there may have been only one or two species existing in the Northern Hemisphere through the entirety of the Cenozoic: present-day G. biloba (including G. adiantoides) and G. gardneri from the Paleocene of Scotland. [23] : 85
At least morphologically, G. gardneri and the Southern Hemisphere species are the only known post-Jurassic taxa that can be unequivocally recognised. The remainder may have been ecotypes or subspecies. The implications would be that G. biloba had occurred over an extremely wide range, had remarkable genetic flexibility and, though evolving genetically, never showed much speciation.[ citation needed ]
While it may seem improbable that a single species may exist as a contiguous entity for many millions of years, many of the ginkgo's life-history parameters fit: Extreme longevity; slow reproduction rate; (in Cenozoic and later times) a wide, apparently contiguous, but steadily contracting distribution; and (as far as can be demonstrated from the fossil record) extreme ecological conservatism (restriction to disturbed streamside environments). [23] : 91
Given the slow rate of evolution of the genus, Ginkgo possibly represents a pre-angiosperm strategy for survival in disturbed streamside environments. Ginkgo evolved in an era before flowering plants, when ferns, cycads, and cycadeoids dominated disturbed streamside environments, forming low, open, shrubby canopies. Ginkgo's large seeds and habit of "bolting" – growing to a height of 10 meters before elongating its side branches – may be adaptations to such an environment.
Modern-day G. biloba grows best in environments that are well-watered and drained, [23] : 87 and the extremely similar fossil Ginkgo favored similar environments: The sediment record at the majority of fossil Ginkgo localities indicates it grew primarily in disturbed environments, such as along streams. [23] Ginkgo, therefore, presents an "ecological paradox" because while it possesses some favorable traits for living in disturbed environments (clonal reproduction) many of its other life-history traits are the opposite of those exhibited by modern plants that thrive in disturbed settings (slow growth, large seed size, late reproductive maturity). [23] : 92
Although Ginkgo biloba and other species of the genus were once widespread throughout the world, its habitat had shrunk by two million years ago.
For centuries, it was thought to be extinct in the wild, [45] but is now a common tree cultivated throughout eastern China, Korea, and Japan. Many municipalities in Korea and Japan use Ginkgos as street trees, and Ginkgo leaves are the emblem of prominent educational institutions such as the University of Tokyo and Sungkyunkwan University in South Korea. Despite their widespread habitat, high genetic uniformity exists among ginkgo trees, with some Chinese scholars suggesting that ginkgo trees in these areas may have been planted and preserved by Chinese monks over about 1,000 years. [46] This study demonstrates a greater genetic diversity in Southwestern China populations, supporting glacial refugia in mountains surrounding the eastern Tibetan Plateau, where several old-growth candidates for wild populations have been reported. [46] [47] Recently, the findings of Ginkgo trees aged 1,500 years in Samcheok-si, Korea (the Neukguri Ginkgo, designated as Korea's natural artifact in 1986), [48] and aged 1,200 in Tsurugaoka Hachimangu Shrine in Japan have discredited theories claiming Chinese origins of Ginkgo.[ citation needed ] Whether native ginkgo populations still exist has not been demonstrated unequivocally, but there is genetic evidence that these Southwestern populations may be wild, as well as evidence that the largest and oldest Ginkgo biloba trees may be older than surrounding human settlements. [46]
Where it occurs in the wild, Ginkgo is found infrequently in deciduous forests and valleys on acidic loess (i.e. fine, silty soil) with good drainage. The soil it inhabits is typically in the pH range of 5.0 to 5.5. [49]
Ginkgo has long been cultivated in China. It is common in the southern third of the country. [49] Some planted trees at temples are believed to be over 1,500 years old. The first record of Europeans encountering it is in 1690 in Japanese temple gardens, where the tree was seen by the German botanist Engelbert Kaempfer. Because of its status in Buddhism and Confucianism, the ginkgo has also been widely planted in Korea and in Japan since the 14th century; [50] in both areas, some naturalization has occurred, with ginkgos seeding into natural forests. Ginkgo has been commonly cultivated in North America for over 200 years and in Europe for close to 300, but during that time, it has never become significantly naturalized. [51]
G. biloba is also commonly manually planted in cities across the United States and Europe. This species is highly tolerant to pollution and serves as a visually appealing, shade-providing tree in many cities and gardens. [52]
Many intentionally planted ginkgos are male cultivars grafted onto plants propagated from seed, because the male trees will not produce the malodorous seeds. The popular cultivar 'Autumn Gold' is a clone of a male plant.[ citation needed ]
The disadvantage of male Ginkgo biloba trees is that they are highly allergenic. They have an OPALS (Ogren Plant Allergy Scale) rating of 7 (out of 10), whereas female trees, which can produce no pollen, have an OPALS allergy scale rating of 2. [53]
Female cultivars include 'Liberty Splendor', 'Santa Cruz', and 'Golden Girl', the latter so named because of the striking yellow color of its leaves in the fall; all female cultivars release zero pollen. [53]
Many cultivars are listed in the literature in the UK, of which the compact 'Troll' has gained the Royal Horticultural Society's Award of Garden Merit. [54] [55]
Ginkgos adapt well to the urban environment, tolerating pollution and confined soil spaces. [56] They rarely have disease problems, even in urban conditions, and are attacked by few insects. [57] [58]
Ginkgos are popular subjects for growing as miniature landscapes known as penjing and bonsai ; [59] they can be kept artificially small and tended over centuries. The trees are easy to propagate from seed.
Extreme examples of the ginkgo's tenacity may be seen in Hiroshima, Japan, where six trees growing between 1 and 2 kilometres (1⁄2 and 1+1⁄4 miles) from the 1945 atom bomb explosion were among the few living organisms in the area to survive the blast. Although almost all other plants (and animals) in the area were killed, the ginkgos, though charred, survived and were soon healthy again, among other hibakujumoku (trees that survived the blast).[ citation needed ]
The six trees are still alive: They are marked with signs at Housenbou (報専坊) temple (planted in 1850), Shukkei-en (planted about 1740), Jōsei-ji (planted 1900), at the former site of Senda Elementary School near Miyukibashi, at the Myōjōin temple, and an Edo period-cutting at Anraku-ji temple. [60]
At the Tsurugaoka Hachiman-gū's shrine in the city of Kamakura, Kanagawa Prefecture, Japan, an ancient ginkgo tree stands beside the stone entry staircase. According to legend, the tree has stood there since the founding of the shrine circa 1063. [61] The tree is nicknamed kakure-ichō (hiding ginkgo), because of an Edo period legend in which shōgun Minamoto no Sanetomo was assassinated in 1219 by his nephew, Kugyō, who had hidden behind the tree to ambush the shōgun. [61]
Modern scholarship has established that ginkgos arrived from China in the 14th century, and a 1990 tree-ring measurement indicated the kakure-ichō's age to be about 500 years. [11]
On 10 March 2010, the tree blew down in a storm, but the stump has since sprouted vigorously. [61]
The grounds of the Buddhist temple at Gu Guanyin in the Zhongnan Mountains feature a ginkgo tree reputed to be 1,400 years old. [62] [63] The tree itself is a popular tourist attraction.
The wood of Ginkgo biloba is used to make furniture, chessboards, carving, and casks for making saké; the wood is fire-resistant and slow to decay. [45]
The nut-like kernels of the seeds are particularly esteemed in Asia, and are a traditional ingredient in Chinese food. Ginkgo nuts are used in congee , and are often served at special occasions such as weddings and the Chinese New Year (as part of the vegetarian dish called Buddha's delight). Japanese cooks add ginkgo seeds (called ginnan) to dishes such as chawanmushi , and cooked seeds are often eaten along with other dishes. Grilled ginkgo nuts with salt are also a popular item at izakayas as a healthy snack with beer and other Japanese food. [64] In Korea, ginkgo nuts are stir-fried and eaten, or are used to garnish foods such as sinseonro. [65]
When eaten in large quantities or over a long period, the seeds may cause poisoning by ginkgotoxin (4'-O-methylpyridoxine, MPN), as found in a few case reports. [66] [67] A heat-stable compound not destroyed by cooking, MPN may cause convulsions, which were alleviated by treatment with pyridoxine phosphate (vitamin B6), according to limited studies. [66] [67]
Some people are sensitive to the chemicals in the sarcotesta, the outer fleshy coating. These people should handle the seeds with care when preparing the seeds for consumption, wearing disposable gloves. The symptoms are allergic contact dermatitis, [68] [69] or blisters similar to that caused by contact with poison ivy. [70]
Although extracts of Ginkgo biloba leaf are often marketed as cognitive enhancers, there is no evidence for effects on memory or attention in healthy people. [8] [71] Systematic reviews have shown there is no evidence for effectiveness of ginkgo in treating high blood pressure, [72] menopause-related cognitive decline, [73] tinnitus, [74] [75] post-stroke recovery, [76] or altitude sickness. [77]
There is weak preliminary evidence for ginkgo affecting dementia [78] [79] [80] and tardive dyskinesia symptoms in people with schizophrenia. [81]
Side effects of using ginkgo supplements may include increased risk of bleeding, gastrointestinal discomfort, nausea, vomiting, diarrhea, headaches, dizziness, heart palpitations, and restlessness. [8] [9] Although use of standardized Ginkgo biloba leaf extracts in moderate amounts appears to be safe, [8] excessive use may have undesirable effects, especially in terms of drug interactions. [9] The dosing of anticoagulants, such as warfarin or antiplatelet medication, may be adversely affected by using ginkgo supplements. [8] [9]
According to a systemic review, the effects of ginkgo on pregnant women may include increased bleeding time, and there is inadequate information about safety during lactation. [9] [82]
Ginkgo pollen may produce allergic reactions. [9] Ginkgo biloba leaves and sarcotesta contain ginkgolic acids [83] – which are highly allergenic – long-chain alkylphenols, such as bilobol or adipostatin A [84] (bilobol is a substance related to anacardic acid from cashew nut shells and urushiols present in poison ivy and other Toxicodendron spp.) [9] [69] Individuals with a history of strong allergic reactions to poison ivy, mangoes, cashews and other alkylphenol-producing plants are more likely to experience an allergic reaction when consuming non-standardized ginkgo-containing preparations. [9] The level of these allergens in standardized pharmaceutical preparations from Ginkgo biloba was restricted to 5 ppm by the Commission E of the former Federal German Health Authority. Overconsumption of seeds from Ginkgo biloba can deplete vitamin B6. [85] [86]
Since 2016, Ginkgo biloba extract is classified as a possible human carcinogen (group 2B) by the International Agency for Research on Cancer. [87]
Ginkgo has been used in traditional Chinese medicine since at least the 11th century C.E. [88] Ginkgo seeds, leaves, and nuts have traditionally been used to treat various ailments, such as dementia, asthma, bronchitis, and kidney and bladder disorders. However, there is no conclusive evidence that ginkgo is useful for any of these conditions. [8] [9] [89]
The European Medicines Agency Committee on Herbal Medicinal Products concluded that medicines containing ginkgo leaf can be used for treating mild age-related dementia and mild peripheral vascular disease in adults after serious conditions have been excluded by a physician. [90]
The ginkgo leaf is the symbol of the Urasenke school of Japanese tea ceremony. The tree is the official tree of the Japanese capital of Tokyo, and the symbol of Tokyo is a ginkgo leaf. Since 1948, the badge of Tokyo University has been two ginkgo leaves (designed by Shoichi Hoshino), which became the university logo in 2004 with a redesign. [91] The logo of Osaka University has been a simplified ginkgo leaf since 1991 when designer Ikko Tanaka created it for the university's sixtieth anniversary. [92]
In professional sumo, wrestlers ranked in the two highest divisions ( jūryō and makuuchi ) wear an elaborate topknot called ōichōmage (大銀杏髷, lit. 'ginkgo-leaf topknot') because it resembles the leaf of the ginkgo tree. [93]
Ginko is an official tree of Seoul since 1971, designated by the Seoul Metropolitan Government. [94]
Ginkgoales are a gymnosperm order containing only one extant species: Ginkgo biloba, the ginkgo tree. The order has a long fossil record extending back to the Early Permian around 300 million years ago from fossils found worldwide.
The Ginkgoaceae is a family of gymnosperms which appeared during the Mesozoic Era, of which the only extant representative is Ginkgo biloba, which is for this reason sometimes regarded as a living fossil. Formerly, however, there were several other genera, and forests of ginkgo existed. Because leaves can take such diverse forms within a single species, these are a poor measure of diversity, although differing structures of wood point to the existence of diverse ginkgo forests in ancient times.
Ginkgoopsida is a proposed class of gymnosperms defined by Sergei V. Meyen in 1984 to encompass Ginkgoales alongside a number of extinct seed plant groups, which he considered to be closely related based on similarities of morphology of pollen, seeds, cuticles, short shoots and leaves. The validity of this group as a whole has been considered questionable by other authors, who consider that it is unlikely to be monophyletic. Other authors have used the class as a monotypic grouping, including only Ginkgoales. Some authors have used the clade Ginkgophyta to encompass both Ginkgoales and Czekanowskiales/Leptostrobales, which are suggested to be closely related groups.
Cycads are seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male or female. Cycads vary in size from having trunks only a few centimeters to several meters tall. They typically grow very slowly and live very long. Because of their superficial resemblance, they are sometimes mistaken for palms or ferns, but they are not closely related to either group.
The gymnosperms (JIM-nə-spurmz, -noh-; lit. 'revealed seeds'
Nageia is a genus of conifers belonging to the podocarp family Podocarpaceae. Nageia includes evergreen shrubs and trees, from one to 54 meters in height. A 2009 treatment of the genus recognized five species. Some authors consider Nageia formosensis to be a separate species from Nageia nagi, thus recognizing six species. The podocarp genera have been reshuffled by various botanists. Most recently, several species formerly classed as Nageia were moved to the new genus Retrophyllum, while Nageia falcata and Nageia mannii were moved to the new genus Afrocarpus.
In botany, a zoid or zoïd is a reproductive cell that possesses one or more flagella, and is capable of independent movement. Zoid can refer to either an asexually reproductive spore or a sexually reproductive gamete. In sexually reproductive gametes, zoids can be either male or female depending on the species. For example, some brown alga (Phaeophyceae) reproduce by producing multi-flagellated male and female gametes that recombine to form the diploid sporangia. Zoids are primarily found in some protists, diatoms, green alga, brown alga, non-vascular plants, and a few vascular plants. The most common classification group that produces zoids is the heterokonts or stramenopiles. These include green alga, brown alga, oomycetes, and some protists. The term is generally not used to describe motile, flagellated sperm found in animals. Zoid is also commonly confused for zooid which is a single organism that is part of a colonial animal.
Ginkgo is a genus of non-flowering seed plants. The scientific name is also used as the English name. The order to which it belongs, Ginkgoales, first appeared in the Permian, 270 million years ago, and Ginkgo is now the only living genus within the order. The rate of evolution within the genus has been slow, and almost all its species had become extinct by the end of the Pliocene. The sole surviving species, Ginkgo biloba, is found in the wild only in China, but is cultivated around the world. The relationships between ginkgos and other groups of plants are not fully resolved.
Ginkgo dissecta is an extinct ginkgo species in the family Ginkgoaceae described from a series of isolated fossil leaves. The species is known from Early Eocene sediments exposed in the province of British Columbia, Canada, and Washington, US. It is one of two Ginkgo species found at the Washington and British Columbia sites.
Ginkgotoxin (4'-O-methylpyridoxine) is a neurotoxin naturally occurring in Ginkgo biloba. It is an antivitamin structurally related to vitamin B6 (pyridoxine). It has the capacity to induce epileptic seizures.
Peter Del Tredici is an American botanist and author. He is a former senior research scientist at Arnold Arboretum for 35 years and a lecturer at the Harvard Graduate School of Design. He was appointed curator of the Larz Anderson Bonsai Collection in 1982 and was editor of the journal Arnoldia from 1989 to 1992.
Ginkgoidae is a subclass of Equisetopsida in the sense used by Mark W. Chase and James L. Reveal in their 2009 article "A phylogenetic classification of the land plants to accompany APG III." This subclass contains the single extant genus Ginkgo under order Ginkgoales, family Ginkgoaceae. Its only extant species is Ginkgo biloba, the Maidenhair Tree.
Ginkgo cranei is an extinct Ginkgo species in the family Ginkgoaceae described from a series of isolated fossil ovulate organs and leaves. The species is known from upper Paleocene sediments exposed in the state of North Dakota, US. It is the first Ginkgo species to be described from Paleogene period with reproductive structures.
Ginkgo huttonii is an extinct Ginkgo species in the family Ginkgoaceae from the Jurassic of England. The fossil is also known by the name, Ginkgoites huttonii, the genus, Ginkgoites, referring to a group of extinct members of the Ginkgoaceae. G. huttonii was a broad-leaved, deciduous gymnosperm bearing resemblance to the only living member of the Ginkgoaceae, Ginkgo biloba.
Ginkgo yimaensis is an extinct ginkgo species in the family Ginkgoaceae. It is a gymnosperm, first described by Zhou and Zhang.
Ginkgo apodes is an extinct species of plant in the order Ginkgoales. It is known from fossils found in the Yixian Formation dated to the Tithonian period, from the Late Jurassic, located near Mount Yinwoshan, Yixian region, Liaoning Province, China.
In biogeography and paleontology, a relict is a population or taxon of organisms that was more widespread or more diverse in the past. A relictual population is a population currently inhabiting a restricted area whose range was far wider during a previous geologic epoch. Similarly, a relictual taxon is a taxon which is the sole surviving representative of a formerly diverse group.
Baiera is a genus of prehistoric gymnosperms in the order Ginkgoales. It is one of the oldest fossil foliage types of Ginkgoales, and is related to the genera Ginkgo and Ginkgoites. Fossils of Baiera are found worldwide, and have been known from the Permian to the Cretaceous.
Celtis biondii is a species of hackberry native to China, Taiwan, Korea, and Japan. It prefers to grow on limestone in the floristic assemblage that is thought to also include wild Ginkgo biloba. It is a deciduous tree growing 18 m (59 ft) tall.
Ginkgo henanensis is an extinct species of seed plant in the family Ginkgoaceae. Fossil specimens of this species are known from Paleocene deposits in Henan, China.
ginkgo tree disease.
According to some sources, the medicinal use of ginkgo dates back to 2800 B.C.… However, the first undisputed written records of ginkgo come much later… Ginkgo first appears in copies of the Shen Nung pharmacopeia around the eleventh and twelfth centuries.